1150 Brake failure

[aussie]

I need some guidance to identify the cause - fix for brake failure on my 2001 1150RT. Mileage: 84K Kilometres.

 

History

This bike has a history of spline failure 39K - 38K and 4K. I have just received it back from the BMW workshop and covered 429 Km after its latest failure and rebuild.

 

I was travelling in stop go traffic on an undulating city road for about 5K. I was constantly on and off the brakes and using the front brake to hold the bike stopped. The constant "meow" from the brake stopped and I rolled back slightly until I applied more pressure. The bottom light came on and stayed on.

 

The traffic moved at a faster rate for about 2K and I did not have to apply the brakes. When I applied them again there was no servo assist and it took a lot of effort to apply enough pressure at the front lever to effect any braking. The rear brake was similar. The bottom light was on and the top light (brake failure) was on and flashing fast.

 

Rode home in city traffic (20Km) without servo assist - not pleasant.

 

I now have it home and after some basic tests this is what I found

 

1. Ignition off battery Voltage 12.88V

 

2. Ignition on

- sound of servo initialising ( from memory standard sound)

- bottom light on

- failure light on and flashing fast

- battery voltage 12.24

- rear light on

-

3. Apply front brake

- no sound

- lights as above

- stop light on ( performs as should at all stages of tests)

- battery voltage 12.19

 

4. Apply rear brake

- low continuous " meow"

- battery voltage 12.10

- apply more pressure on pedal - "meow" deeper tone

battery voltage 11.98v

- also apply front brake

- "meow" increases in volume

- rear brake pulses in unison with application of Fr brake

- battery voltage 11.98v

 

I was hoping the latest trans rebuild would solve this persistent problem and I need a new problem "like a hole in the head"

 

Could something as simple as - loose, crimped wire etc from the rebuild have caused this problem. Electrics are not my favourite thing so could someone suggest some basic procedures to follow to find the cause. I have read other posts on this topic but did not pay much attension as I concentrated on splines.

 

Your help would be appreciated.

 

cheers

 

george

 

[dirtrider]

Morning Aussie

 

Per #2 above:

 

2. Ignition on

- sound of servo initialising ( from memory standard sound)

- bottom light on

- failure light on and flashing fast

- battery voltage 12.24

- rear light on

 

If by rear light you mean rear brake light then it sounds like you might have a sticking bake light switch. If the rear brake light lights WITHOUT using either the front brake lever or rear pedal that usually indicates a sticking brake light switch.

 

I guess worth perusing that first.

 

 

Edit: seeing as the brake light circuits on that I-ABS system work in reverse logic if you have the rear brake light staying on all the time that the key is turned on it might be a stuck switch or could be a cut or disconnected wire between the front or rear brake light switch and ABS controller. (an open will turn the brake light in)

[Paul Mihalka]

Problem 1: The clutch splines. You have a 2001 R1150RT which corresponds to the 2002 R1150 bikes in the USA. These bikes have a reputation of repeated spline features, suspected because a bad batch of gear box housings that put the splines out of alignment. If your bike was repaired by only replacing the clutch and the gearbox input shaft, it will fail again.

Problem 2: Brakes. As you describe your first ride, it may have ended up with low voltage in the battery provoking the malfunction. With continuous riding the battery charged up again, so your voltage readings are good. In your last paragraph it sounds like the problem/error indications corrected by itself, as you seem to have the servo brakes again. I would put the battery on a charger and then test ride it. The brake problem may be fixed. The clutch spline problem is not.

[aussie]

Sorry I need to clarify a few points.

 

1. At all times the tail light and the brake light respond correctly - tail light on when ignition on, brake light on when brake applied and off when brake released.

 

2. When the rear brake is applied the results are as described in my original post plus the following:

- when the rear brake pedal is released the constant "meow" continues and only stops when the ignition is turned off. If the blue relay is removed the brake failure light goes out but the noise continues/

 

Cheers

 

george

[dirtrider]

Morning George

 

Thanks for the update, that helps a little but still not enough info to pinpoint the problem. Your mention of servo pump running is a little confusing in relation to other actions.

 

Are you saying at first Key on (engine not running)

 

Tail light is on?

 

Brake light is off?

 

ABS servo pump NOT running?

 

OR -ABS servo pump runs all the time?

 

With front brake lever depressed Brake light comes on?

 

With front brake lever then released Brake light goes off?

 

With rear brake lever depressed Brake light comes on?

 

With rear brake lever then released Brake light goes off?

 

Does ABS servo pump run ALL the time ignition switch is turned on?

 

Does ABS servo pump ever turn off with the key turned on?

 

Does ABS pump noise get louder when front brake ever is squeezed harder?

 

Does ABS pump noise get louder when rear brake ever is squeezed harder?

 

 

--Engine running now--

 

When bike is ridden slowly do you have power assist when using the front brake lever?

 

When bike is ridden slowly do you have power assist when using the rear brake lever?

 

 

Maybe with answers to the above questions we can get you closer to the problem.

 

On the I-ABS servo systems the best way to get real answers is to have the dealer read the ABS stored failure codes as that usually tell what is failed now and what has failed in the recent past.

 

[Bigfish]

Do you hear the tiny click of your micro switches when gently pushing down on the rear brake or slowly pulling the front brake lever?

 

I had the same problem recently and it turned out to be a small pebble making the rear brake microswitch stay engaged. If a microswitch is engaged before startup, the Servo Assist will not deploy.

 

Listen for the little clicks.

 

Good Luck!

[aussie]

Morning George

 

Thanks for the update, that helps a little but still not enough info to pinpoint the problem. Your mention of servo pump running is a little confusing in relation to other actions.

 

Are you saying at first Key on (engine not running)

 

Tail light is on? Yes

 

Brake light is off? Yes

 

ABS servo pump NOT running? Appears to initialise in normal way (sound)

OR -ABS servo pump runs all the time? No

 

With front brake lever depressed Brake light comes on? Yes

 

With front brake lever then released Brake light goes off? Yes

 

With rear brake lever depressed Brake light comes on? Yes

 

With rear brake lever then released Brake light goes off? Yes

 

Does ABS servo pump run ALL the time ignition switch is turned on? No ??

Pump appears to initialise , one or 2 seconds max, when ignition first turned on - from memory this is normal.If the front brake is applied the pump does not run. If the rear brake is applied then the pump runs continuously even when the brake is released.

 

Does ABS servo pump ever turn off with the key turned on? Front does not energise pump Rear brake applied pump runs - release rear brake pump still runs.

 

Does ABS pump noise get louder when front brake ever is squeezed harder? Front not activated by application of brake.

 

Does ABS pump noise get louder when rear brake ever is squeezed harder? Yes. Also when front brake operated rear brake pulses in unison

 

 

--Engine running now--

 

When bike is ridden slowly do you have power assist when using the front brake lever? No

 

When bike is ridden slowly do you have power assist when using the rear brake lever? No

 

Checked microswitch at brake pedal and can hear it activate when brake applied and released. I do not know where to check it electrically.

 

Maybe with answers to the above questions we can get you closer to the problem.

 

On the I-ABS servo systems the best way to get real answers is to have the dealer read the ABS stored failure codes as that usually tell what is failed now and what has failed in the recent past.

 

That will be my final resort as I would have to travel throught the city centre to get to my nearest dealer. Not a very nice thought after my experience riding it home after initial failure.

 

I appreciate your input and I trust the above answers clarify the situation. I can follow diagnostic suggestions but not initiate them..

 

cheers

 

george

[dirtrider]

Morning George

 

Your ABS light flashing and general warning light on tells us what we already know, that is you have no brake power assist.

 

The rear brake light working from both front and rear levers tells us the micro switches are more than likely working OK.

 

The rear pump staying on after rear brake use but the brake light going back off at pedal release tells us the problem is more than likely internal to the ABS controller itself.

 

The brake light working from the front lever but the ABS pump not initiating when the lever is pulled tells us something is amiss in the ABS controller.

 

Honestly, your next move will probably be finding a way to read the stored and current ABS stored failure codes.

 

A real (at home) long shot would be to completely bleed the control and servo sides of the ABS system while looking for signs of air and contaminated fluid.

 

Another real long shot would be to disconnect the battery for a while to see if the ABS controller was somehow confused with a stray voltage spike. (this is a real long shot)

 

As of the info we have at hand now your problem seems to be internal to the ABS controller.

 

Years ago I worked on an I-ABS system that acted similar and best I could determine it was caused by someone previously bleeding the ASB system with the large wire harness plug removed and getting brake fluid into that connector therefore into the internal ABS circuitry. Maybe remove the large plug on the ABS controller and look for signs of brake fluid or moisture down in that connector. If so, possibly get the last place that worked on or bled the system to take some responsibility for the failure.

 

[AndyS]

Hi George,

The bike reverting to residual braking is VERY frightening - I've been there.

Having to ride anywhere afterwards shattered my confidence in the system, iether because it might stop working at any time - or just as worrying - if it started to work again after a failure.

 

Your symptoms sound similar to my experience. I had the fault code read by my BMW Dealer and the readback told me internal pressures were outside tolerance. The bill was in excess of £50 for the priveledge. The next advice from them was to get the iABS servo unit replaced....

I had checked the tail light and brake light - all OK.

I re-bled all the systems - no help

I checked the wiring from the ABS sensors - all OK

I checked the front brake microswitch signal at the Servo large electrical connector - all OK

Then checked the rear brake micro switch at the large electrical connector - all OK

After more consultation with folk on this and other boards, I removed the Sevo completely and reverted to traditional brakes.

They work brilliantly BUT I do miss the idea of not having ABS anymore.

 

If you choose to remove the Servo, I have a good walkthrough that I can send you for a step by step proceedure.

 

Andy

[jrparodi]

You can also read the ABS codes with a GS-911, if you or a conveniently located friend has one- might save you a trip to the dealer...

[aussie]

I would appreciate your offer of a walk through on removing the servo system. As you can see from my original post I have had 3 spline failures - the last on only 4K (Kms) after a complete rebuild - and now this after only a few hundred Km since it was put back on the road. I don't want to spend a fortune repairing the servo only to have the splines go again.

 

cheers

 

george

[Dave Parry]

BUT I do miss the idea of not having ABS anymore

----------------

 

AndyS, is it not possible to remove the servo but still keep ABS? (as on R1100RT)

Dave.

[Boffin]

BUT I do miss the idea of not having ABS anymore

----------------

 

AndyS, is it not possible to remove the servo but still keep ABS? (as on R1100RT)

Dave.

 

No, the servo is an integral function of the ABS controller. That said, it would probably be possible to retro-fit a R1100RT ABS system to an 1150. The controllers are similar in size - it would just be a matter of rigging the wiring/brake lights/hydraulic lines.

 

Andy

[dirtrider]

Morning Andy

 

The wheel speed input is also different so the old 1100 tone rings and wheel sensors would need to be fitted (if even possible).

 

[aussie]

G'day all

 

Your input was very welcome if discouraging. Had another fiddle tonight after work.I wanted to have a general look around to see if a wire or connection had been damaged during the rebuild and check the servo fluid levels.

 

The following finding is probably a symtom if not a cause of my problem and it maybe of interest as an early warning sign of pending failure.

 

The front and rear resevoirs were at the correct level.

The rear resevoir had clear fluid but

the front resevoir had fluid which was a dark chocolate colour. I syphoned the old fluid out and refilled with clean brake fluid. I then opened the brake bleed nipple at the caliper and gravity bled and collected the fluid in a glass jar. The fluid ran freely and was a chocolate colour which then cleared as the new fluid flushed through the system. Both fr & rear systems were flushed at the same time approx. 18 months ago.

 

Question: what are the 2 identical electrical connections to the left of the resevoir filler caps?

 

cheers

 

george

[dirtrider]

Morning George

 

Those two connectors are for the internal ABS controller reservoir fluid level detection.

 

On your brake fluid color differences. That is probably due to the rear having been bled when the splines were done, the front probably wasn’t .

 

Now that you have (some) new fluid in the front you might try riding on a real bumpy road using the brakes and trying to get the ABS to initialize (careful if you have the failure lights on as you probably have no ABS available). With old skunky fluid in the controller maybe something stuck in there that might free up when jarred on a bumpy road.

 

If you can get it working maybe that new fluid will cycle though and keep it working (yep! A long shot at best)

 

[NonComp]

When I bought my '96 with 60K miles on it, I found that the fluid was dark chocolate at the ABS unit, even after bleeding clear fluid at the wheels. By mine is an ABS 2 system. I mention this because I think it is a good idea to bleed at the ABS unit too once in a while, just to be on the safe side.

 

How long ago was your front wheel circuit bled? I wonder why someone would bleed the rear circuit but not the front?

[dirtrider]

I wonder why someone would bleed the rear circuit but not the front?

 

Morning NonComp

 

Because the rear brake circuit was probably opened to lift the rear for trans removal to replace spline shaft.

 

[NonComp]

Interesting. I guess if I was the owner of this bike, I'd wonder why, if the brake fluid in the rear circuit came out chocolate brown, they didn't flush the front as well.